Bad Glow Plug Symptoms Every Driver Must Know

Do you know how does an engine starts effectively? It needs a heating component known as a diesel glow plug. Until and unless this special glow plug generates the heat, the engine can’t start. The glow plugs are seen in vehicles that have diesel engines. The main motive of this plug is to supply enough heat so that that engine warms up nicely before starting. When your vehicle doesn’t start in the colder environments, this plug functions to generate the required heat inside. Otherwise, it would be tough for the engine to process further. But, you will sometimes see the bad glow plug symptoms too, which is when you need to replace it or fix it.

Bad Glow Plug Symptoms

Some symptoms will always show up when the glow plug has gone bad. We just need to keep our eyes open to sense what these signals are trying to tell us. Also, be ready with some maintenance tips as that can at least help you survive an unwanted situation that might occur because of the bad glow plug.

You must know that it is time to replace the glow plug, when:

Exhaust Pipe Throws Out Black Smoke

When the exhaust pipe starts throwing out black smoke, consider it as a sign that the diesel glow plug has gone bad. Bad glow plug limits diesel combustion that results in black smoke out of the exhaust pipe. Yes, there are several other reasons why you can see that black smoke coming out of your car. But, you should inspect this plug too, once that dark black smoke is witnessed.

Bad glow plug symptoms
Bad glow plug limits diesel combustion that produces black smoke. (Photo Source: wallpapercave)


Struggle to Start Engine

Once the plug has gone bad, it will not allow the engine to start so quickly. Simply put, you will see a struggle there when starting the vehicle. The ignition will begin, but only after pressurising the engine too much. So, when you see that happening in your vehicle, make sure to replace that glow plug immediately.

Engine Light is ‘ON’

The engine light will turn on when there is malfunctioning in the glow plug. Experts recommend using a diagnostic scan tool to identify the issue in the vehicle. Look for this code- P0380. It is the warning code to understand that the glow plug has malfunctioned. And, that’s the best time to replace it by reaching the best professionals nearby.

Repeated Engine Misfires

The engine begins to work when the fuel inside the vehicle is ignited aptly. That will not happen in the case of bad glow plug. Hence, engine misfires. Diesel plug glow is essential to generate appropriate heat inside the engine. When that doesn’t happen (because the diesel glow plug is bad) there will certainly be trouble in starting the engine.

Bad glow plug symptoms
Diesel plug glow is essential to generate heat inside the engine. (Photo Source: narpro)


Bad glow plug symptoms will always try and hint you when there is something wrong with the glow plug. It is crucial to identify these issues and fix them to enhance the overall performance of the vehicle.